1 files changed, 66 insertions, 0 deletions
diff --git a/vendor/github.com/letsencrypt/boulder/goodkey/weak.go b/vendor/github.com/letsencrypt/boulder/goodkey/weak.go
new file mode 100644
index 000000000..4a63af09a
--- /dev/null
+++ b/vendor/github.com/letsencrypt/boulder/goodkey/weak.go
@@ -0,0 +1,66 @@
+package goodkey
+
+// This file defines a basic method for testing if a given RSA public key is on one of
+// the Debian weak key lists and is therefore considered compromised. Instead of
+// directly loading the hash suffixes from the individual lists we flatten them all
+// into a single JSON list using cmd/weak-key-flatten for ease of use.
+
+import (
+	"crypto/rsa"
+	"crypto/sha1"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+)
+
+type truncatedHash [10]byte
+
+type WeakRSAKeys struct {
+	suffixes map[truncatedHash]struct{}
+}
+
+func LoadWeakRSASuffixes(path string) (*WeakRSAKeys, error) {
+	f, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	var suffixList []string
+	err = json.Unmarshal(f, &suffixList)
+	if err != nil {
+		return nil, err
+	}
+
+	wk := &WeakRSAKeys{suffixes: make(map[truncatedHash]struct{})}
+	for _, suffix := range suffixList {
+		err := wk.addSuffix(suffix)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return wk, nil
+}
+
+func (wk *WeakRSAKeys) addSuffix(str string) error {
+	var suffix truncatedHash
+	decoded, err := hex.DecodeString(str)
+	if err != nil {
+		return err
+	}
+	if len(decoded) != 10 {
+		return fmt.Errorf("unexpected suffix length of %d", len(decoded))
+	}
+	copy(suffix[:], decoded)
+	wk.suffixes[suffix] = struct{}{}
+	return nil
+}
+
+func (wk *WeakRSAKeys) Known(key *rsa.PublicKey) bool {
+	// Hash input is in the format "Modulus={upper-case hex of modulus}\n"
+	hash := sha1.Sum([]byte(fmt.Sprintf("Modulus=%X\n", key.N.Bytes())))
+	var suffix truncatedHash
+	copy(suffix[:], hash[10:])
+	_, present := wk.suffixes[suffix]
+	return present
+}